The majority of commercially available powder-free latex gloves are manufactured by first preparing a powdered glove on-line and then removing the powder from the glove by chlorination and rinsing off-line. The chlorination process oxidizes the natural rubber surface of the glove thereby providing improved dry donning characteristics. Chlorination also removes any powder deposited on the gloves during the rinsing operation.
Other powder free gloves have been produced by using powder free coating technology in combination with chlorination or other post treatment processes. Some of these coated gloves use a manufacturing process which requires that the rubber substrate be treated with acid or other harsh chemicals to improve adhesion of the coating to the base rubber glove. This additional chemical processing step is not preferable in glove manufacturing because the chemicals used are generally corrosive and/or difficult to handle in large scale production processes. Additionally, most of the coated and non-coated gloves do not have acceptable donning characteristics with respect to damp and wet skin, which is one of the critical product requirements for surgical glove applications. Finally, some of these gloves also exhibit self-sticking between the inner glove surfaces which create difficulties for health care workers trying to don the gloves in a sterile environment.
The present invention provides a powder-free, inner-nitrile rubber coated, natural rubber or synthetic elastomer glove for medical and industrial applications which has good donning characteristics and good grippability (as measured by the coefficient of friction of the donning and gripping surfaces). The glove of the invention also exhibits good tensile strength, stress at 500% elongation and elongation to break.
The inner coating on the gloves of the invention is a cross-linked nitrile rubber blended with a lubricant. Interposed between the nitrile rubber coating and the base elastomeric glove is an intermediate layer of a rubber blend comprised of natural or synthetic rubber and nitrile rubber. Comparative testing demonstrates that the inventive gloves have improved adhesion between the coating and the base glove as compared to those coated gloves which do not contain the intermediate layer of rubber blend. The gloves of the invention do not show any appearance of surface sticking between the inner surfaces and/or the outer surfaces and also exhibit good donning with respect to both dry and wet skin. The inventive gloves also have a unique surface texture which improves donnability.